External frequency conversion of cw mode-locked Ti:Al_2O_3 laser radiation

Abstract

Efficient frequency conversion of cw mode-locked Ti:Al2O3 laser radiation using lithium triborate, β-barium borate, and lithium iodate crystals as the nonlinear material is demonstrated. Second-, third-, and fourth-harmonic generation results in tunable blue and ultraviolet radiation down to 205 nm with transform-limited pulses and pulse lengths below 1 ps. Maximum average powers (repetition rate 82 MHz) of 700 mW at 400 nm, 120 mW at 272 nm, and 10 mW at 210 nm were obtained. The effects of group-velocity dispersion have to be taken into account to optimize the different frequency-conversion processes.